The Flow Cytometry Unit is an interdepartmental resource of the NYU Cancer Institute at the NYU Medical Center whose objective is to make available state-of-the-art flow technology service and training to the members of the Cancer Center. These services are designed to facilitate the research of the members, educate them about the technological possibilities offered by flow techniques and train preand - post-doctoral students in the use of this technology. The facility operates three instruments: a Coulter EPICS Elite sorter, a Becton Dickinson LSR analyzer and a Becton Dickinson FACScan analyser. These are centrally housed on the 3rd floor of the Skirball Institute. The Flow Cytometry Core Laboratory provides sensitive multiparameter cell marker analysis; quantitative studies of DNA content; kinetic measurements of intracellular Calcium and pH; measurement of membrane fluidity as well as quantitation of the interactions of particles coated with cell adhesion molecules. Analytical quality control is maintained by daily standardization of the instruments with reference beads and by the routine inclusion of reference samples. The laboratory also provides cell-sorting capabilities. Sample preparation is the responsibility of the users of the facility. Cell selection can be performed on up to five parameters at rates to 5,000 cells/second. A single cell deposition device (AutoCIone) is available that maintains sterility and permits the instrument to be used for cloning cells. All members of the Center have access to the facility on a first come, first served basis. Cancer Center members have priority over non members. The facility is supported by a combination of user fees, institutional support and the Cancer Center Core Grant.